Telephone system



Patented Oct. 17, 1939 PATENT OFFICE TELEPHONE SYSTEM Knrt'Baloun, Be'rlin-Haselhorst, Germ-my, as-

slgnor to Siemens & llalske Aktiengesellschai't, Wernerwerk. Siemensstadt, near Berlin, Germany Application February 11, ms, Serial No. 189,551 In Germany February 28, 1937 4 Claims. (Cl. 179-85) I The invention relates to a circuit arrangement for remote control systems and more particularly for telephone systemahaving party lines whose branch stations are equipped with switches (step- 5 ping switches or relay selectors) which are adapted to be set by impulses. In such systems a large number or branch stations can be selectively connected to the common line but diiilculties are involved when it is a question oi. eiiiciently operating the many receiving devices arranged in parallel. In systems known hitherto. the attempt has been made touse considerable sending energies at the sending station or to provide very sensitive receiving devices at the receiving stations. Neither solution, however, is completely satisfactory, since on the one hand the use of large sending energies prejudices the efficiency of the system since both large sources oi sending current must be used and the lines and apparatus must be particularly well insulated, while on the other'hand when using small sending energies and accordingly sensitive receiving devices the tendency to faults in the system becomes very 7 great and the efllciency in operation suflers. The invention avoids these disadvantages in that the branch stations are divided into groups and during selection only the impulse receiving device controlling the switches'at the branch stations oi the group characterized by'the type or the course of the selecting current are influenced in dependence upon the type (alternating current of particular frequency, direct current in a particular direction) or by the course of the selecting current used for impulsing. The system is so arranged that blocking means are providedat the branch stations and only allow the impulse receiving devices controlling the switches (stepping switches or relay switches) to be influenced upon the reception of selecting 40 current characterizing the corresponding group or branch stations. Thus in a selecting operation, even. in the case of systems with a great number of branch stations. only the relatively few branch stations of the desired group are traversed by the current so that it is possible to control normally equipped devices efliciently with only small sending energies.

As blocking devices at the branch stations known filter circuits can be used in the event oi 5.0 alternating currentot different frequencies being used as the selecting current, while it direct current in diiierent directions is used as the selecting current valves, for example, rectiilers, glowlamps or the like can be used as blocking devices I at the branch rtations. In order to accommodate a large number of groups of branch stations, the receiving devices controlling the switches at the branch stations can be arranged in series with the blocking devices either between the two leads of the party line or between one lead and earth.

. The attached drawing shows a number of embodiments of the invention to which the latter, however, is not limited.

Figure 1 indicates the principle or the inven- 10 tion in quite general form, while Fig. zshows an arrangement using direct current in different directions as the selecting current and, Fig. 3 shows an arrangement for systems in which alternating current of diflering frequencies constitutes the selecting current.

In'the embodiments the branch stations connected to the party line, which as regards the calling, selecting and speaking devices can be constructed in any known manner, are only di- 2 agrammatically represented. At these stations are arranged in series with the receiving devices controlling the switches W the blocking devices Sp which only allow selecting current of a particular type to pass to the switches. As receiving Q5 devices, separate receiving'relays may be provided or alternatively, the stepping magnets of the switches can themselves be connected to the line.

I-Gr. IX) are indicated. Each branch station shown represents a group comprising any number of similarly constructed stations. The system is so arranged that branch stations of the groups Gr. IGr. III are controlled over the a-lead of 35 the party line GL and earth, while the stations of the groups Gr. IVTGr. VI are controlled over the b-lead and earth and the stations of the groupsGr. VII-Gr. IX are controlled over the two leads of the party line. Thus when selecting so current is connected for example-to the a-lead and earth, only the stations of the groups Gr. L-Gr. III are influenced. A further division is obtained by the kind of selecting current applied, so that only the receiving devices at the stations as oi the desired group, for example Gr. 11, are traversed by the selecting current, so that in fact only'the energy required for the efllcient controlling oi the receiving devices ofthis one group need be supplied from the sending station. Corso responding operations take place when selecting subscribers oi the other groups.

In order to obtainsecret working with such a system a seizing impulse may be transmitted for each group shortly after initiating a call so that In Fig. 1, nine branch stations (groups Gr. 30

are brought into the busy condition in the known manner.

In the arrangement shown in Fig. 2 a system is represented in which direct current in different directions is used as the selecting current. Thus six groups of subscribers are provided, while any number of similar stations may be contained in each group. The switches oi. the groups Gr. I and Gr. II are controlled over the b-lead and earth, the switches of the groups Gr. III and Gr. IV over the a-lead and earth and the swtiches of the groups Gr. V and Gr; VI over the two leads of the party line. At the branch stations the switches W are represented diagrammatically as stepping switches. When selecting the subscriber II, for example, positive potential is applied to the b-le'ad and the current consequently flowing is interrupted a number of times in accordance with the call number of the desired subscriber. By the application of positive p61- tential to the b-lead actually only the receiving devices of the group Gr. I are influenced since the blocking devices at the stations of the group Gr. 11 whose switches are also connected between the b-lead and earth prevent the flow of current at these stations. Thus on transmitting impulses only the receiving devices of the stations oi group Gr. I are influenced.

Similar operations take place when selecting stations of other groups. As blocking devices,

- rectiiiers, for example are provided which only permit the passage 01' current in one direction. These rectiiiers can be replaced by other devices which only allow current to pass in one direction, for example glow-lamps or the like.

8. 3 shows an arrangement in which alternating current of diflerent frequency is used as the selecting current. As blocking devices $17 which .are indicated diagrammatically at the subscribersstation ll, fllter circuits are used,

' lecting current connected to the common line is these comprising choke-coils and condensers in the known way. These filter circuits enable only current of a quite deflnite frequency or frequency range to traverse these blocking devices, so that when selecting current of this type is transmitted only the receiving devices in series with these blocking devices can be influenced. The stations of the various groups can be connected with their selecting devices, as shown diagrammatically in Fig. 1, either between the a-lead and earth or between the b-lead and earth, or

between the aand b-leads of the party line GL,

to be called, alternating current of definite fre- ,quency is applied to both leads of the party hue by the sending station- On account of the blocking devices Sp this alternating current can only traverse the receiving devices of the group 4 Gr. VII. Thus only the switches at the stations of this group are advanced when the seinterrupted on impulsing.

2,176,321 the receivlng devlces at all the branch stations The number of groups of branch stations can be increased at willby using alternating current of diil'ering frequency. It is also possible, however, to combine systems as indicated in Figs. 2 and 3, and in this way to increase the number of groups. It is thenonly necessary to provide vspecial blocking devices (filter circuits)at the stations according to Fig. 2 to block the passage of alternating current of any frequency to the receiving devices, while in the case of the staof direct current.

What is claimed is: 1. In a telephone system, a line, a plurality of stations selectable over said line, each station having a' selecting device connected to the line, the devices of-one'group of said stations responsive only to impulses transmitted over one side of the line, the devices of another group of said stations responsive only to impulses transmitted over the other side 01' the line, and the devices of still another group .of said stations responsive only to impulses transmitted over the two sides of the line in series, each device operated by said impulses to select its associated station responsive to the receipt of a predetermined number of impulses.

2. A telephone system as. claimed in claim 1, wherein there are rectiflers and the devices of each group of stations are connected to the. line through said rectifiers so that each of. said groups is divided into two subgroups, the devices of one subgroup of each group responding only to impulses of one polarity, the devices of the other subgroup of that group responding only to impulses of the opposite polarity.

3. A telephone system as claimed in claim 1, wherein there are alternating current filters and the devices of each group of stations are connected to the line through said alternating current filters so that each of said groups is divided into a plurality of subgroups, the devices of each subgroup of a group responding only to alternating current impulses of a frequency different from that to which the devices oi. other subgroups oi. that group respond.

4. In a telephone system, a multi-station line, a plurality of the stations having impulse counting means connected in series with two conductors of the line and operated in unison only by impulses of potential connected across the conductors, another plurality of the stations having grounded impulse counting means connected to one of said conductors and operated in unison only by impulses of potential connected to said one conductor, and still another plurality of 'the stations having grounded impulse counting means connected to the other of said conductors and operated in unison only. by impulses of potential connected to said other conductor, the individual stations in each plurality, of stations distinguished from the other stations in that plurality by din'erent numbers of operations of the counting .means.

. 1 KURT BALOUN. 

